Yeats once said 'too long a sacrifice can make a stone of the heart', Amy Lowell echoes the same sentiments here in relation to loving someone you shouldn't.
A Fixed Idea - Amy Lowell
What torture lurks within a single thought
When grown too constant; and however kind,
However welcome still, the weary mind
Aches with its presence. Dull remembrance taught
Remembers on unceasingly; unsought
The old delight is with us but to find
That all recurring joy is pain refined,
Become a habit, and we struggle, caught.
You lie upon my heart as on a nest,
Folded in peace, for you can never know
How crushed I am with having you at rest
Heavy upon my life. I love you so
You bind my freedom from its rightful quest.
In mercy lift your drooping wings and go.